Hungry fledglings receive order: Go hunt

Friday

Jun 24, 2011 at 2:00 AM

It's started. The whining, that is. Feed me. Feed me! FEED ME!!!

By Stewart Janes

It's started. The whining, that is. Feed me. Feed me! FEED ME!!!

It's late June, and young birds are spilling out of nests all over the valley and chasing after mom and dad, asking for just one more free meal. Parents are doing their best, but it never seems to be enough.

The first young red-tailed hawk just fledged in my neighborhood. It's not an event easily missed. The young bird on unsteady wings is certain mom and dad have no idea where it is. As a result, it fears it may miss a meal. Believe me, from the loud, grating and persistent cries it is in no danger of being forgotten, not by anyone within a quarter of a mile.

I'm tempted to toss it a mouse in the hopes of just a few minutes of peace and quiet. Soon the trees along the Bear Creek Greenway and around the foothills of the valley will be filled with noisy, demanding young.

In June, the cries of hunger are just an irritation, but soon begging becomes much more serious. By July, the tough love starts. Mom and dad begin to cut back on rations. They offer the young a little less than needed to fill the belly. If the young wish to be sated, they must supplement the parental rations with their own effort. They must learn to hunt. This is not exactly what the fledgling is hoping for. It's been a free ride up to this point, and now it has to start earning a living for itself.

With each passing day parents offer a little less. With each day, the young must get a little more proficient at finding prey.

The food offered by the parents stretches out the time to independence, but by early August it better have the hunting thing figured out.

As a rule of thumb, two out of three young birds of prey die in their first year of life. We often think of the rigors of winter as the time of greatest peril. There are losses at this time to be sure, but the period of greatest mortality is August. This is the time when young birds that fail to acquire adequate hunting skills gradually starve. Only the skilled, agile and clever birds survive.

Couldn't the parents feed the young just a little bit longer and give the challenged young a little more time? The answer is apparently not. Summer is the time adult red-tailed hawks and most other birds must grow a completely new set of feathers. This takes a considerable amount of energy. If the adult is to survive, it needs to conserve the energy needed to complete its molt by mid to late September in time to begin migration and before the relative abundance of summer fades away.

It may seem cruel, but it ensures that only the keenest of predators carry on. A young red-tailed hawk that survives to wear the reddish-orange tail of an adult at one year of age has my profound respect. Still, it is hard to endure the plaintive cries of the hungry fledglings in July. Now where did I leave that bucket of mice?

Stewart Janes is a biology professor at Southern Oregon University. He can be reached at janes@sou.edu.